| Species: Swainson's Thrush
Catharus ustulatus
Description:
Swainson's Thrushes
are a member of the Thrush family, in the Catharus genus with other
similar looking North American thrushes. Two main subspecies groups
exist; Pacific and Boreal. The Pacific have more russet colored
upperparts, compared with more olive-brown upperparts in the Boreal
populations.
It is well known for its flute-like upwardly spiraling song
frequently heard at dusk and dawn during the breeding season.
Swainson's Thrushes breed principally across the boreal forest from
Alaska to Newfoundland, but also south through the Rocky and Coast
Mountains. Their wintering range is through southern Mexico, Central
America, and northern South America.
Identification:
General: Medium
sized songbird. Adults measure about 17 cm long and weigh about 30
grams.
Adult: Sexes
alike, although males are slightly larger than females. Warm brown
upperparts, including tail and rump, with whitish underparts with
black spotting in the throat and upper breast, legs pinkish, and
bill pinkish with a black tip. Distinctive for Swainson's Thrushes
are cream coloured eye-rings and lores giving a 'spectacles' look.
Juvenile:
Similar to adults, however like all Catharus thrushes young birds.
Similar Species:
Hermit Thrush has a reddish tail and rump and has and a whitish
eye-ring. Gray-cheeked Thrush is a 'colder' brown colour, with a
grayish cheek patch, and brown tail and rump. Veery generally has
lighter brown upperparts, with brown tail and rump, mostly lacking
an eye-ring, breast spots are more brownish or grayish and
upper-breast washed with gray or light brown.
Behaviour:
Generally inconspicuous on the forest floor or shrub layer. Forages
by kicking up leaf litter and will more frequently fly-catch from
shrubs than other thrushes. Usually hops along the ground, with its
tail held upright, occasionally pumping its tail.
Habitat:
Forest, including deciduous, mixed or coniferous. During the
breeding season they are usually found in coniferous forest,
typically spruce-fir forest, although they will use riparian forest
in more southerly populations. In winter they frequent rainforest
and second growth areas. During migration they are known to use a
variety of habitats, but require a dense understory for protective
cover.
Information:
Swainson's
Thrushes, while primarily insect eaters during the breeding season,
utilize late summer and fall berry crops to increase fat loads for
migration and to provide additional energy during cold winter
weather. Birds will frequent open or disturbed areas, such as bogs,
clearcuts and burns to take advantage of high berry production in
these areas. Frequently found in mixed species flocks during
migration.
Swainson's Thrushes breed from April to June and typically have one
brood per year, however two have been reported in some areas. Most
clutches have four eggs, but known to vary between one and four,
with an incubation period of 10-14 days, and fledging after 10-14
days.
During the breeding season most Catharus thrushes in BC segregate
themselves by elevation or habitat. Swainson's Thrushes are found
primarily in lower elevation forest and Hermit Thrushes in upper
elevation forest in BC. Veery's, while found in low-land forest, are
found in more riparian areas than Swainson's Thrushes.
Conservation
Status: (Least Concern)
Populations are slightly decreasing throughout range. Some habitat
loss on both the breeding and wintering grounds may be of concern,
but large range and population size indicate overall it is fairly
secure.
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